1. Field of the Invention
The present invention relates to a thin film magnetic recording head used as, for example, a floating magnetic head and the like, and particularly to a thin film magnetic head in which an upper core layer can precisely be patterned, and a magnetic path formed by lower and upper core layers can be shortened, and a method of manufacturing the thin film magnetic head.
2. Description of the Related Art
FIG. 9 is a partial sectional view showing the structure of a conventional thin film magnetic head (inductive head), and FIG. 10 is a partial sectional view of the thin film magnetic head taken along line Xxe2x80x94X line in FIG. 9, as viewed from direction A.
In FIGS. 9 and 10, reference numeral 1 denotes a lower core layer made of a magnetic material such as permalloy or the like, and an insulation layer 3 is formed on the lower core layer 1.
The insulation layer 3 has a trench 3a which is formed in the depth direction from the surface (referred to as xe2x80x9cABSxe2x80x9d hereinafter) facing a recording medium to have an inner width dimension equal to a track width Tw.
The trench 3a contains a bottom pole layer 4 magnetically connected to the lower core layer 1, a gap layer 5, and a top pole layer 7 magnetically connected to an upper core layer 6, which are formed by plating in turn from the bottom.
As shown in FIG. 10, the top pole layer 7 formed on the gap layer 5 is formed with a predetermined length dimension Gd from the ABS in the depth direction (the Y direction shown in the drawings), and a Gd setting insulation layer 8 is formed to extend in the depth direction from a portion of the top of the gap layer 5 which is located at the back of the cop pole layer 7 to a portion of the top of the insulation layer 3 which is located at the back of the trench 3a of the insulation layer 3. The Gd setting insulation layer 8 is made of, for example, a resist material. The length dimension Gd of the top pole layer 7 corresponds to the gap depth which has a great effect on the electric properties of the thin film magnetic head, and is thus set to a predetermined length dimension by forming the Gd setting insulation layer 8.
As shown in FIG. 10, a coil layer 9 is formed in a spiral pattern on the insulation layer 3 with the Gd setting insulation layer 8 provided therebetween. The coil layer 9 is made of a conductive material having low electric resistance, for example, such as Cu or the like.
The coil layer 9 is covered with a coil insulation layer 11 made of an organic material or the like, and the upper core layer 6 is formed by plating a magnetic material such as permalloy or the like to extend from the top pole layer 7 to the coil insulation layer 11. As shown in FIG. 9, the width dimension T1 of the upper core layer 6 exposed in the ABS is larger than the track width Tw, and the upper core layer 6 is magnetically connected to the top pole layer 7 formed in the trench 3a of the insulation layer 3.
In the write inductive head, when a recording current is supplied to the coil layer 9, a recording magnetic field is induced in each of the lower core layer 1 and the upper core layer 6 so that magnetic signals are recorded on the recording medium such as a hard disk or the like by a leakage magnetic field between the bottom pole layer 4 and the top pole layer 7 magnetically connected to the lower core layer 1 and the upper core layer 6, respectively.
In the inductive head shown in FIG. 9, the insulation layer 3 is formed on the lower core layer 1 and has the trench 3a which is formed with a predetermined length L1 from the ABS in the depth direction (the Y direction shown in FIG. 9). The trench 3a can be formed by, for example, anistropic etching, to have a width dimension in submicron unit.
In the inductive head shown in FIG. 9, the inner width dimension of the trench 3a is defined as the track width Tw so that the bottom pole layer 4 and the top pole layer 7 magnetically connected to the lower core layer 1 and the upper core layer 6, respectively, are formed with the gap layer 5 provided therebetween within the track width Tw. Therefore, a leakage magnetic field produced between the bottom pole layer 4 and the top pole layer 7 can be produced in the narrow track width Tw, thereby making the inductive head adaptable for track narrowing accompanying with increases in recording density in future.
However, in the structure of the thin film magnetic head shown in FIGS. 9 and 10, the coil layer 9 is formed on the C;d setting insulation layer B formed on the insulation layer 3, and thus the height dimension H1 from the top of the top pole layer 7 to the top of the coil insulation layer 11, which covers the coil layer 9, is very large.
With a large height dimension H1, there is a problem in that the upper core layer 6 cannot be precisely patterned to extend from the top pole layer 7 to the coil insulation layer 11.
The upper core layer 6 is formed by a so-called frame plating process which comprises coating a resist layer in a region ranging from the top pole layer 7 to the coil insulation layer 11 shown in FIG. 10, and then patterning the resist layer in the shape of the upper core layer 6 by exposure and development.
However, with the large height H1 from the top of the top pole layer 7 to the top of the top of the coil insulation layer 11, the resist layer formed on the top pole layer 7 has a large thickness, thereby increasing the focal depth in exposure and development. Therefore, the wavelength of an exposure light source is shortened to increase the focal depth. In this case, resolution (resolving power) deteriorates, and particularly, the tip portion 6a of the upper core layer 6 cannot be formed in a predetermined shape on the top pole layer 7.
Furthermore, since the thickness of the resist layer formed on the top pole layer 7 greatly differs from the thickness of the resist layer formed on the coil insulation layer 11, irregular reflection occurs due to a difference in focus in exposure and development, and thus the upper core layer 6 cannot be precisely patterned in the resist layer.
In the thin film magnetic head shown in FIG. 10, the Gd setting insulation layer 8 formed below the coil layer 9 is formed by spin-coating a resist material or the like on the insulation layer 3.
However, since the Gd setting insulation layer 8 is formed by spin coating, waviness occurs on the surface, and thus formation of the coil layer 9 on such a waviness surface causes a problem in that the coil layer 9 cannot be patterned in an appropriate shape due to a focal disturbance in exposure and development of the resist layer used for forming the coil layer 9.
Therefore, the pitch T2 of the coil layer 9 is increased to permit appropriate patterning of the coil layer 9 to some extent. However, in this case, an increase in the pitch T2 of the coil layer 9 enlarges the entire size of the coil layer 9, and thus the length dimension from the chip portion 6a to the base end 6b of the upper core layer 6 must be increased to lengthen the magnetic path formed by the upper core layer 6 and the lower core layer 1, thereby causing the problem of increasing inductance.
Also, when the height dimension H1 from the top of the top pole layer 7 to the top of the coil insulation layer 11 is increased, the upper core layer 6 must be formed with a long length. Therefore, in the thin film magnetic head shown in FIG. 10, the magnetic path is further lengthened to readily increase inductance.
The present invention has been achieved for solving the above conventional problems, and an object of the present invention is to provide a thin film magnetic head in which an upper core layer can be precisely patterned, and the length of a magnetic path can be shortened to prevent an increase in inductance, and a method of manufacturing the thin film magnetic head.
A thin film magnetic head of the present invention comprises a lower core layer made of a magnetic material, an upper core layer made of a magnetic material, and an insulation layer located between the lower and upper core layers and having a trench which determines the gap width, all of which appear on the surface facing a recording medium, wherein the upper and lower core layers are laminated with a gap layer provided therebetween in the trench, and a coil layer is formed directly on a portion of the insulation layer, which is located at the hack of the trench in the height direction, for inducing a recording magnetic field in each of the upper and lower core layers.
Conventionally, a Gd setting insulation layer is formed between a coil layer and an insulation layer formed on a lower core layer, for defining the gap depth. However, in the present invention, the coil layer is formed directly on the insulation layer, and thus the height dimension from the position (for example, the top of the top pole layer 24 shown in FIG. 2) where the tip portion of the upper core layer is formed to the top of a coil insulation layer formed on the coil layer can be decreased, as compared with conventional heads. Therefore, the upper core layer can be precisely patterned to extend from the position where the tip of the upper core layer is formed to the coil insulation layer.
In addition to the advantage that the height dimension from the position where the tip portion of the upper core layer is formed to the top of the coil insulation layer formed on the coil layer can be decreased, the coil layer is patterned directly on the flat surface of the insulation layer to decrease the pitch of the coil layer, thereby decreasing the length dimension from the tip of the upper core layer to the base end thereof, as compared with a conventional head.
Therefore, in the present invention, the length of a magnetic path formed by the lower core layer and the upper core layer can be shortened to permit a reduction in inductance.
In the present invention, the Gd setting insulation layer may be provided on the insulation layer to extend in the depth direction from a back portion of the trench to a portion of the insulation layer surface where the trench is not formed, and the coil layer is not formed, and the upper core layer may be formed on the Gd setting insulation layer from the surface facing the recording medium so that the gap depth is determined by the facing-surface-side front end of the Gd setting insulation layer.
Namely, in the present invention, the Gd setting insulation layer and the coil layer are formed at the same level (on the surface of the insulation layer), and thus even with the Gd setting insulation layer formed, the height position of the top of the coil insulation layer from the position where the tip of the upper core layer is formed is not raised, thereby permitting precise patterning of the upper core layer.
In the present invention, a bottom pole layer magnetically connected to the lower core layer, a gap layer, and a top pole layer magnetically connected to the upper core layer are preferably formed by plating in turn from the bottom in the trench formed in the insulation layer.
In this case, the Gd setting insulation layer may be provided on the insulation layer to extend in the depth direction from a back portion of the top pole layer to a portion of the insulation layer surface where the trench is not formed, and the coil layer is not formed, and the upper core layer may be formed on the top pole layer and the Gd setting insulation layer from the surface facing the recording medium so that the gap depth is determined by the dimension from the surface facing the recording medium to the boundary between the top pole layer and the Gd setting insulation layer.
The present invention also provides a method of manufacturing a thin film magnetic head comprising a lower core layer made of a magnetic material, an upper core layer made of a magnetic material and opposed to the lower core layer with a nonmagnetic gap layer provided therebetween on the surface facing a recording in medium, and a coil layer for inducing a recording magnetic field in each of the lower and upper core layers; the method comprising the step of forming an insulation layer on the lower core layer and forming a trench in the insulation layer in the height direction from the surface facing the recording medium, for defining a track width; the step of forming a bottom pole layer magnetically connected to the lower core layer, the gap layer, and a top pole layer magnetically connected to the upper core layer in the trench by plating in turn from the bottom; the step of patterning the coil layer directly on a portion of the insulation layer, which is located at the back of the trench in the depth direction; the step of forming a coil insulation layer on the coil layer; and the step of forming the upper core layer on the tope pole layer and the coil insulation layer.
The surface of the insulation layer formed on the lower core layer is planarized, and the coil layer is patterned directly on the flat surface so that the coil layer can be readily and securely patterned with a narrow pitch.
In the present invention, since the coil layer is patterned directly on the insulation layer, the height dimension from the surface of the top pole layer (the surface where the tip of the upper core layer is formed) formed in the trench of the insulation layer to the top of the coil insulation layer formed on the coil layer can be decreased, as compared with a conventional head.
Therefore, in the present invention, the upper core layer can be precisely patterned on the top pole layer and the coil insulation layer by frame plating.
Also, in the present invention, the Gd setting insulation layer may be formed to extend in the depth direction from a back portion of the trench to a portion of the insulation layer surface where the trench is not formed, and the coil layer is not formed, the tope pole layer may be formed between the surface facing the recording medium and the Gd setting insulation layer in the trench, and the upper core layer may be formed on the top pole layer and the Gd setting insulation layer so that the gap depth is determined by the dimension from the surface facing the recording medium to the boundary between the top pole layer and the Gd setting insulation layer.